Multiple switch boaed



(No Model.) 3 Sheets-Sheet I.

W. S. FORD.

MULTIPLE SWITCH BOARD. No. 357,821. Patented Feb. 15, 1%8'7.

lflll U WITNESSES: IN

3 Sheets-Sheet 2.

(No Model.)

W. S, FORD.

MULTIPLE SWITCH BOARD.

Patented Feb. 15, 1887.

ImJL

(No Model.) 3 Sheets-Sheet 3.-

W. S. FORD. MULTIPLE SWITGH BOARD.

No. 357,821. Patented Feb. 15,1887.

Figl0 5* i; z E 7 I k 7 WiTNESE E51 TNVENTUTKI UNITED TATES WILLIAM srnnonn FORD,

PATENT OFFICE.

OF DENVER, COLORADO.

MULTIPLE SWITCH-BOARD.

SPECIFICATION forming part of Letters Patent No. 357,821, dated February 15, 1887.

Application filed July 6, 1886. Serial No. 207,172.

To aZZ whom it may concern:

Be it known that I, VVILLIAM SPENCER FORD, of Denver, in the county of Arapahoe and State of Colorado, have invented certain new and useful Improvements in Multiple Switch-Boards for Telephone-Exchanges, of which the following is a specification.

This invention relates to multiple switchboards which are employed at central stations in telephone-exchange systems, and affords facilities whereby several attendants can work simultaneously in making connections between the subscribers lines entering the station, there being one section or division of the switch-board for each operator. Each of said sections or divisions has switching facilities, which are duplicates of those of the other sections of the board, so that any operator can connect any two of the subscribers lines entering the station.

Myinventionhasforitschiefobject toprovide means whereby the act of connecting two lines at any section of the switch-board will visually indicate at all the other sections the fact that the connected lines are in use, and will also break the connection between the lines in use and the an'nunciators for said lines.

To these ends the invention consists in the combination of, first, a series of rods, hereinafter termed linerods, forming parts of the subscribers lines and adapted to be rotated in the frame-work of the switch-board; secondly, a series of connecting-rods ateach section of the switch-board movable longitudinally in said frame and arranged crosswise of the line-rods, and connected to thelatter by coupling deyices, the arrangements being such that a longitudinal movement of a connectingrod in any section of the switchboard is caused to partially rotate the line-rod to which it is coupled and through said linerod move the connecting-rods coupled thereto in all the other sections of the switchboard: and, thirdly, devices whereby an operator can establish an electrical connection between any two of the conneotingrods in a section, and thus connect the two line-rods which are coupled to said connecting-rods, each connectingrod being coupled to one linerod only,

there being as many connecting-rods in each section as there are line-rods, each line-rod having its'own connecting-rod in each section. l

(No model.)

The invention also consists in certain details, all of which I will now proceed to describe and claim.

Of the accompanying drawings, forming a part of this specification, Figure 1 represents a top view of a multiple switch-board embodying my invention. Fig. 2 represents an edge or front viewof the same. Fig. 3 represents a section on line y 3 Fig. 1. Fig. irepresents a section on line 2 a, Fig. 1. Figs. 5, 6, 7, 8, and 9 represent detail views. Figs. 8 and 8 show modifications. Fig. 10 represents a top view of a modification or extension.

The same letters of reference indicate the same parts in all the figures.

In the drawings, M M represent the frame of my multiple switch-board, the same being constructed in any suitable manner and having its front and back sides divided into operators sections of convenient length. Six sections are here shown, of which three are at the front and three at the back; but it is obvious that any other convenient number of sections may be arranged in one frame.

A A, &c., represent the line-rods, which are connected to the subscribers lines, each line entering the station being connected to one end of a rod, A, the other end of said rod being normally connected to ground by means hereinafter described. The line-rods are supported and adapted to turn or rock in crossbars N, forming parts of the frame M.

In each section of the switch-board is a series of connectingrods, a, corresponding in number to the total number of line-rods, said connecting-rods extending crosswise of the line-rods and being adapted to move longitudinally inguides or tubes 6 e, inserted in the front and back of the frame. Each linerod is so linked or coupled to a connecting rod in each series as that a longitudinal movement imparted by the operator to any connecting-rod will partly rotate the line-rod coupled thereto and move the other connectingrods coupled to the same line-rod longitudinally in the same direction and to the same extent as the connecting-rod moved by the operator. In this instance there are three series of connecting-rods; hence each line-rod is coupled to three connecting-rods, and said i connecting-rods are moved simultaneously by pressure applied to either of them.

The coupling devices shown in this instance are arms f, attached to the line-rods A, and angular pieces 0, which are secured to the connecting-rods a, and are provided with slots 0 formed as shown in Figs. 3 and 4, to receive the arms f, and permit the same to stand vertically, as shown in Fig. 3, or at an incline, as shown in Fig. et, the slots being contracted at their middle portions and widened in either direction outwardly. Each arm f is preferably composed of two arms and a loop that encircles the line-rod A, and is secured to said rod by a screw, S, which passes through the two arms and clamps the loop upon the rod.

I prefer to make each connecting-rod win two parts, which are connected by the offset pieces 0, as by so doing I am enabled to place the slots 0, which receive the arms f, either above or below the rods a, as shown in Fig; 3, for a purpose hereinafter described. To

- the ends of the connecting-rods a are affixed heads or push-pieces h, of brass or other conductor of electricity. These heads are adapted to slide in the tubes 6, and when they are in their normal positions their outer ends are. flush with the front and rear surfaces of the frame M, as shown in Fig. 3.

Springs interposed between washer w and the inner ends of heads h normally hold the connecting-rods in the position shown in Fig. 3, said washers being pressed by the springs against inwardly-turned flanges e on the inner ends of the tubes 6, which flanges support the springs and enable them to normally hold the connecting-rods, as above indicated. The washers w bear against collars r, attached by set-screws to the connecting-rods a.

It will be seen by the foregoing that as the rods to are conductors of electricity and are in electrical contact with the line-rods A, each line-rod having its own connecting-rod upon each section, the establishment of an electrical connection between any two of the connecting-rods will, through said rods, connect the two line-rods coupled thereto, and as a consequence the two lines represented thereby. The devices which I use for making the connections are two plugs, d d, which are connected by a conduetingcord, d. In practice a pair of conducting-cords are employed, united to one another through suitable keys or switches,

whereby each or both united lines may be connected at pleasure with call apparatus, with the operators telephones, or with a clearing out annunciator in a manner well understood.

The operation of connecting any two subscribers linessay numbers 3 and 5-is performed by inserting the plugs d d in the tubes containing the heads h of the connecting-rods linked to line-rods 3 and 5. This operation establishes an electrical connection between the said two connecting-rods by the contact of the plugs d d with the heads of said rods, and also moves the said rods longitudinally from their normal positions, thus causing them to partly rotate line-rods 3 and 5, and through said line-rods to move the connecting-rods linked to line-rods 3 and 5 in all the other sections of the switch-board, as shown in Fig. 1. A visual indication is thus given in all the sections of the switch-board that lines 3 and 5 are in use. This indication of the condition of the lines consists in the fact that upon the side of the switch-board at which the connection is made the corresponding rods ends are all depressed, while the same rods upon the sections at the other side of the board are seen to project beyond the plug-socket orifice. Thus any connectingrod which projects beyond or which is depressed behind the face of the switch-board denotes a line in use, while each rod end flushwith the face of the board denotes that the line it represents is at rest and is free for another connection. When the operator desires to disconnect the connected subscribers lines, she simply withdraws the plugs d, whereupon the springs K return the displaced connecting-rods and line-rods to their normal positions, thus electrically connecting the lines with their annunciators.

The plugs d (I may be made wholly or in part of brass or other suitable metal, and are preferably split and thus made compressible at their inner ends, so that when inserted in the tubes 6 they may be compressed, and thus caused to exert sufficient pressure on the inner surfaces of said tubes to prevent the springs K from forcing them out of said tubes. The plugs have shoulders g, which limit the extent to which they may be inserted in the tubes 6, and therefore prevent the plugs from moving the connecting-rods too far. r

In Fig. 9 I have shown the outer end of the tube 0 extended outside of the frame to form spring-jaws adapfid to grasp the shoulder q, and thereby hold the plug more positively against the pressure of the spring K, pressing against the displaced connecting-rod.

The ends of the line-rods A opposite to those ends to which the subscribers lines are connected are provided with laterally-projecting pins Z Z, which, when the line-rods are in their normal position, bear against contact-springs p, which are connected through annunciators X to ground. When any line-rod is turned, as above described, by the displacement of a connectiug-rod coupled to it, the partial rotation of the line-rod turns the pins Z of said line=rod out of contact with the springs p, and thus breaks the connectionbetween the line and the annunciator and earth terminal while the line is in use.

I prefer to arrange the connecting-rods a of each series in two rows, the rods of one row being above and alternating with those of the other. In other words, half of the connectingrods in each series are farther from the linerods than the other connecting-rods, and the higher connecting rods alternate with the lower, as shown in Fig. 3. This arrangement gives a greater distance between each connectingrod and the next than there would be if the rods were all in the same line or plane, and

enables the operator the more readily to find.

IIO

any particular number. In this connection the utility of the ofiset pieces 0, which receive the arms f, will be apparent, said pieces being turned downwardly from the higher connecting'rods and upwardly from the lower connecting-rods, as shown in'Fig. 3, thus locating the slots 0 of all the rods at the same distance from the plane of the line-rods, which is es sential, in order that the line-rods turned by the higher connecting-rods may be moved to the same extent as those turned by the lower connecting-rods.

It will be seen that a multiple switchboard having my improvements above described can be made in very compact form. The linerods A need not exceed three sixteenths of an inch in diameter when made at least fortyfive feet long, and each can have fifteen con nectingrods linked or coupled to it, said connectingrods representing fifteen sections at the front and fifteen sections at the back of the switch; board, and accommodating thirty operators. These operators can attend to between five and six thousand subscribers, and, if necessary, three operators can he placed at every two-sections. This fundamental principle I have elaborated practically, and have embodied in a switching apparatus of the following construction, which works very satisfactorily: The board has four hundred line rodsA, each rod coupled to two connecting-rods, thus making four operators sections-two in front and two at the back. Each section is three feetlong, thus making the board and all the main rods six feet long. The height of the board itself is six and one-fourth inches. Each operator has, of course, the four hundred subscribers before her in a space thirty-six inches wide by six and one-fourth inches high. Two thousand subscribers would occuy a space at each operators section of thirty-six inches wide by thirty-one and one-fourth inches high. In the same manner five thosand subscribers would occupy a space of forty-five inches wide by sixty-two and one-half inches high. There are five layers or courses of the line-rodseighty in a layer. The rods of each layer are threeeighths of an inch apart from center to center. Each layer is one and one-fourth inch above the layer below it. In these spaces between the layers the connecting-rods are brought out.

The resistance of a subscribers circuit through twenty operators sections is only one eighth of one ohm. A subscribers circuit is not taken through contact-points at each operators section, as in other multiple switch boards, and may be insulated from the nearest neighboring by an air-space of three sixteenths of an inch or more, even in boards of the largest capacity, dry air being one of the best insulators known. The specific inductive capacity of air is much less than that of dialectrics generally used; hence there is much less induction and leakage than in other mul- 3 tiple switch-boards.

The collars r on the connectingrods a contance from the heads h to the inner ends of the tubes 6. If the two springs of each connectingrod could always be made ofequal strength the collars and washers would not be necessary. In practice it is found difficult to make and keep these springs of exactly the same strength, and if one is stronger than the other it will push its connecting rod head slightly out of the board and pull the other head slightly into the board. It is desirable, therefore, that some device be made that will always bring the con nectingrods back properly, regardless of variations in the strength of the springs. The placing of stops r and Washers w 011 the crossrods accomplishes this perfectly, as it is evident that the compressed spring K in Fig. 4. will expand and bring the connecting-rod to its proper position upon the removal of plug d, even if the other spring is ten times the stronger, because the powerofthe other spring for the present is entirely taken off from the end of its tube 6, and is confined between the stop 1' and the head h. Therefore its power is annulled until the connecting-rod is returned to its normal position. It is to be noticed that washer w of the compressed spring in Fig. I is hearing on the end of the tube 6, and the whole power of the compressed spring will tend to return the displaced connectingrod a to its normal position. hen in its normal position the washers of both springs will be at the ends of the tubes 6. The work of returning a connecting-rod to its normal position is .always done by the spring which has been compressed, and it never has to overcome the expansion of the opposite sprlng.

Fig. 10 shows how a line-rod in one board can be coupled to one in another board, thus making it possible to operate two boards as if they were but one and doubling the capacity of the exchange. In the figure the two line rods A are linked or coupled together at one end by a cross rod, a, long enough to connect the two boards and coupled to each of the main rods A in exactly the same manner as the other cross-rods.

If necessary or desired, all rods can be coated with an insulating material to prevent their becoming crossed, even if by accident they should touch. In practice I do not find that this is necessary. I prefer to string short rubber tubes along the rods to insure their keeping their proper places; but even this precaution is unnecessary.

I do not confine myself to any particular metal in the construction of the rods, tubes, couplings, 81c.

Heretofore and prior to my invention all multiple switch boards have either been provided with spring-jack contacts for each line upon each section, in which case the lines have required to be looped to the said springjacks, necessitating a complication of apparatus electric circuit, while the several connectionrods of each line extending right and left to the face of each section may be regarded as normally open or incomplete branch circuits, terminatingin connecting plug-sockets. The insertion of a plug-connector in the socket at either end of any one of these branch circuits not only establishes a closed alternative or derived circuit by means of the plug and the flexible conductor connected therewith, but also simultaneously and mechanically transfers the main line to the said alternative route only, by disconnecting the original earth-terminal, and, furthermore, provides a visual signal at each switch-section throughout the central station, denoting that such action has been taken. Thus I combine the simplicity of the single-wire plug socket branches with the efficiency heretofore only obtained by the loop plan.

It will be understood that I do not restrict myself to any special location of the annunciators X, since it is obvious that the drawings, being purely diagrammatic, merely indicate their position in the circuit, and in practice the annunciators would preferably be arranged in groups, a certain number being allotted to each section.

I may, without departing from the spirit of my invention, adopt any well-known equivalent device in place of the pins l, Which,when in their normal position, serve to maintain continuity between the main-line rods and their annunciators and earth-terminals. I may, for example, employ a pair of cams, c" c, in electrical connection with one another, as shown in Fig. 8; or upon the end of the main rod I may fix a non-conducting disk, V, which, at two opposite points upon its periphcry, is provided with conducting-pieces e 6 united electrically through the substance of the said disk, as shown in Fig. 8.

- By the construction I have described,wherein each group of connectionrods and the lines appertaining thereto can be operated from two sides, I effect great economy in construction and in space, and am, in fact, enabled to work six operators in a space not greatly exceeding that required heretofore for butthree. I regard this feature of my invention as being of the highest importance By my invention it is impossible'that any line should at any time be manipulated without at once indicating the fact at all sections by a visual signal, and I find these automatic signals very advantageous in practice, since they are involuntarily operated by the attendant in the act of inserting a plug, and are an advance over any which have heretofore been utilized,in that they are operated by mechanical devices only, and hence do not imply any complicated arrangement'of auxiliary circuits and electro-magnetic appliances.

Having now fully described my invention, I claim- 1. The combination, in atelephone-exchange switching apparatus, of aseries of conductingrods representing main lines,two or more transverse conducti ng-rods articulated to each linerod, each transverse rod constituting a normally-open branch of the main circuit,a single earth branch or extension for each line-rod normally in electrical contact with its own main line and including an electro-magnetic signal-receiving instrument, and means, as indicated, for uniting the open branches of any main circuit with those of any other circuit and for simultaneously and automatically disconnecting the two main lines so united from their normal earth-terminals, whereby both lines are transferred from the said earthterminals and completed through each other, substantially as described.

2. In a multiple or sectional telephoneexchange switching apparatus, a series of main-line circuits, each normally completed through an earth-terminal branch,including an aununciator, a series of normally-open branch circuits for each main line,oue branch to each switchsection, connecting devices, substantially as described herein, for uniting any two norinally-open branches of any two lines and for simultaneously disconnecting the normal earth-terminals ot' the said two lines, and me chanicallyoperated visual signals, one for each line,upon each switch-section to indicate when any line is in use, the same being automatically actuated by the operation of connecting any two lines.

3. A multipleorsectionaltelephone exchange switching apparatus comprising the following elements in combination: a series of main-line circuits, each normally completed through an earth-terminal branch, including an annunciator or like signatreceiving instrument, a series of normally-open branch circuits for each main line, one branch to each section of the multipleswitch apparatus, means, as indicated, for simultaneously connecting any of the normally-open branches of one line to a similar branch of any other line and disconnecting the main line from its normal earthterminal, and automatically actuated visual line-in-use signals, one for each line, upon each switclrsection, adapted to indicate the use or disuse of any and all of the said lines, substantially as and for the purposes specified herein.

4. In atelephoue-exchange sectional switchboard, the mechanical linein-use signal consisting of a series of transverse rods, one for each line, at each switchboard section, both extremities of each of the said rods being sup ported in a plug-socket flush with the outer edge of the said socket, and all the transverse rods of each line being coupled or linked to a single rod supported at a right angle therewith, whereby when any one of the rods at any switch-section is displaced by the insertion of a connecting-plug in the plug'socket thereof the corresponding rods at each other section suffer a like displacement, the ends thereof being either projected beyond or depressed below the edge of the plug sockets in which they are supported, thus constituting a visible indication of the condition of the line.

5. In atelephone-exehange switclrboard,the combination, substantially as hereinbefore described, of a partly-rotatable main-line rod constituting a portion of a main line, an earthterminal branch, and an annunciator included therein, normallyunited to the said main-line rod and "completing the circuit thereof, but adapted to be disconnected therefrom upon the partial rotation of the said main rod, one or more transverse rods articulated to each of the said main-line rods and constituting normally-open branches of the main circuit, both ends of each transverse rod being terminated in plug-sockets flush with the outer edge of the said sockets, plug and cord connectors for uniting any two normally-open branch circuits and the main lines thereof and for effecting simultaneously the disconnection of the earthterminals of both lines by insertion of the said plugs into the said sockets, whereby the ends of the said branch circuits are electrically connected through the plugs and conducti ng-eord, the main rod being at the same time partly rotated to effect the disconnection of the normal earth-terminal, and a visual line-in-usesignal consisting of the position of the end of the articulated transverse rods of each line with respect to the edge of the several plugsockets thereof.

6. The combination of a multiple switchboard in which all of the lines entering the station are branched to each several section with an automatic mechanically-actuated visual line-in-use signal for each line at each switchboard section, each signal consisting of a spindleinclosed in the plug-socket and movable longitudinally therein, the several spindles of each line being mechanically articulated to a common actuator, whereby the movement of any one causes the corresponding movement of the others, for the purpose of visually indicating the use of any line at any switch-board at each and all of the other sections by the position of the spindle end in the plug-sockets, substantially as'described.

7. In a telephone-exchange switching apparatus, independent switch sections located upon and constituted by the two opposite sides of ahollow parallelogram, a series of rods (representing and connected in circuit with an equal number of main lines) extending from end to end of the said parallelogram between the operative sides or opposite series of sections thereof, the said rods being partly rotatable in bearings, a series of transverse rods linked or articulated to each line-rod and supported at each extremity in plug sockets formed in the opposite switch-sections, the ends being normally flush with the external edge of the said plug-sockets, and the entire rod being longitudinally movable therein, so that when any one transverse rod of a series is longitudinally moved the linerod linked thereto will be partly rotated and the longitudinal motion be thereby imparted to each transverse rod similarly linked to the line'rod, and plug-connectors adapted to fit the said plug-sockets at each switch-section for effect ing the said longitudinal motion, all in combination, whereby the insertion of a plug-connector and the consequent use of any line at any individual section is automatically indicated at each and all of the other sections upon one side of the parallelogram by the protrusion of the transverse rod extremity representing such line beyond the edge of its socket and at the sections on the other side by the depression of the corresponding transverse rod extremities below the edge of the sockets, substantially as hereinbefore described, and for the purposes indicated or specified.

8. The eombination,in atelephoneexchange switch apparatus, substantially as described J herein, of partlyrotatable main-line rods and transverse branclrcircuit rodslinked or articulated thereto,as described,switch-sections double in number to the transverse rods, the said switch-sections being arranged in pairs, back to back, with an intervening space, which space ineloses the line and transverse rods, and plugsockets in each'section supporting therein the extremities of the transverse rods, the opposite extremities of each rod being supported in corresponding plug sockets of the opposing sections of a pair, whereby one transverse rod for each line is enabled to serve two switchsections, for the purposes specified.

9; In a switchboard substantially of the character herein specified, the combination of parallel mainline rods representing a single line, each mounted in bearings and partly rotatable therein, a series of two or more transverse connecting'rods linked or articulated to each of the parallel main rods, and an extension-rod uniting the parallel main rods, whereby the motion of either of the said parallel main rods, or any of the transverse branches thereof, may be imparted to the other, for the purpose described.

10. The combination, in an electrical switchboard of the class described herein and comprising a number of duplicate sections, of a series of partly-rotatable rods representing and connected with main circuits, earth-terminal extensions therefor normally completing each main circuit to ground, a circuit-changer for each main-circuit rod controlling the connec tion of each rod with its earth-terminal extension, the said circuit-changer being actuated by the rotation or partial rotation of the said main rod,and means, substantially as indicated, for effecting the said rotation from any one of the said switch-sections, for the purpose specified.

11. In a telephone switch-board, the combination of aseries of line-rods, each adapted to rotate and each connected with a subsc'ribers line, and two or more duplicate series of longitudinally-movable connecting-rods extending crosswise of the line-rods and linked or coupled thereto, substantially as described, whereby the displacement of a connecting-rod in any series will turn or partly rotate the line-rod coupled thereto, and through said line-rod will similarly displace the corresponding connecting rod or rods in the other section or sections.

12. In a telephone switch-board, the combination of aseries of line-rods, each adapted to rotate and each connected with a subscribers line, two or more duplicate series of longitudinally movable connecting rods extending crosswise of the line-rods and linked or coupled thereto, as described, so that an endwise movement of a connecting rod will partly turn or rotate the line-rod coupled thereto and move cndwise all the other connectingrods coupled to said linerod, and springs whereby said connecting-rods are returned to and held in their normal positions after each displacement.

13. In a telephone switch-board, the combination ofa series oflinerods, each adapted to rotate and 'each connected with a subscribers line, two or more duplicate series of longitudinally-movable connecting-rods extending crosswise of the line-rods and linked or coupled thereto, as described, each line-rod being coupled to one connecting-rod in each series, sockets or tubes containing the extremities of said connecting-rods, and plugs electrically connected in pairs and adapted to be inserted in said sockets, and thereby to make contact with the ends of the connectingrods and at the same time move or displace said rods longitudinally, substantially as and for the purpose specified.

14. In a telephone switch-board, the combination of a series of line-rods, each adapted to rotate and each connected with a subscriber s line, two or more. duplicate series of longitudinally movable connecting rods extending crosswise of the line-rods and linked or coupled thereto, as described, sockets or tubes containing the extremities of said connectingrods, springs whereby said connectingrods are normally held in place, removable connecting devices or plugs adapted to be pressed against the ends of said connecting-rods to both make electrical contact with and displace said rods against the pressure of their springs, and ineans,substantially as described, whereby the plugs are held in the position they occupy when displacing the springs, as set forth.

15. In a telephone switchboard, theucombination of a series of rotary line-rods con nected with the subscribers lines, and each having laterally -projecting pins, contactsprings connected through annunciators or other signals to ground and normally in contact with the pins of the line-rods, and lineconnecting devices, substantially as described, through which any line-rod may be connected with another line-rod and by the operation of which the connected linerods are turned or rotated and thereby disconnected from their annunciators, as set forth. 

